An anti-fuse is an electrical device that performs the opposite function to a fuse. For example, a fuse starts with a low resistance and is designed to permanently break an electrically conductive path (typically when the current through the path exceeds a specified limit); whereas, an anti-fuse starts with a high resistance and is designed to permanently create an electrically conductive path (typically when the voltage across the anti-fuse exceeds a certain level).
Anti-fuses are widely used to permanently program integrated circuits (ICs). For example, certain programmable logic devices (PLDs), such as structured ASICs, use anti-fuse technology to configure logic circuits and create a customized design from a standard IC design. As an illustration, an electrically programmable anti-fuse can be used for electrical chip ID (ECID) and SRAM, and logic circuit repair with redundancy rows/columns (SRAM) or logic blocks.
Anti-fuse PLDs are one time programmable in contrast to other PLDs that are SRAM based and which may be reprogrammed to fix logic bugs or add new functions. Anti-fuse PLDs have advantages over SRAM based PLDs in that like ASICs, they do not need to be configured each time power is applied. Also, circuits built via the anti-fuse's permanent conductive paths may be faster than similar circuits implemented in PLDs using SRAM technology.